Field of the Invention
The present invention relates to a toner, a two-component developer, and a color-image forming apparatus.
Description of the Related Art
In an image forming apparatus, such as an electrophotographic image forming apparatus and an electrostatic recording apparatus, an electrostatic latent image formed on a photoconductor (hereinafter may be referred to as an “electrostatic latent image bearer” or “electrophotographic photoconductor”) is developed to form a visible image with a toner, the visible image is transferred onto a recording medium, such as paper, to form a transferred image on the recording medium, and the transferred image is fixed by application of heat and pressure, to thereby form an image. When a full-color image is formed, four color toners; i.e., black, yellow, magenta, and cyan toners are generally used for developing, and visible images for respective colors are transferred and put on top of one another on a recording medium, followed by fixing with heat and pressure.
In order to reduce a load to the global environmental, there is a need for a toner further improved in low temperature fixing ability. In an attempt to allow the toner to soften at lower temperature in order to improve the low temperature fixing ability of the toner, it is necessary for the release agent in the toner to melt at low temperature. However, there is a problem that the release agent melting at low temperature volatilizes during output of images, attaches to an exhaust filter, and thus degrades exhausting performance of the exhaust filter.
Moreover, in order to ensure reliability of images, it becomes important to ensure charging stability of the developer. In particular, there is a problem that use of the release agent melting at low temperature under an environment of high temperature and high humidity (for example, 45° C. in temperature, and 80% RH in humidity) causes spent of the release agent on a carrier of a two-component developer (which may be referred to as “carrier spent”), lowering charging stability.
Therefore, it is difficult to improve resistance to the spent property of a release agent melting at low temperature.
Meanwhile, as a method for softening the toner, it is proposed to use a crystalline resin as a binder resin of the toner (see, Japanese Examined Patent Publication No. 04-024702).
However, it is difficult to solve the aforementioned problems only by using the crystalline resin as the binder resin.